Apparatus for gasifying coal



March 26, 19 57 c. E. ALLEMAN 2,786,660

APPARATUS FOR GASIFYING COAL Original Filed Jan.- 5, 1948 2 Sheets-Sheet l a 28 flaw '41!!! A EHHEIIHIE ivlggjflF" H61 2 INVENTOR.

' C. E. ALLE MAN mfg March 26,1957 c. E. ALLEMAN APPARATUS FOR GASIF'YING COAL Qriginal Filed-Jan. 5. 1948 2 Sheets-Sheet 2 My m: a I

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INVENTOR. c. E. ALLEMAN BY @rToR/m s United States Patent Original application January 5, 1948, Serial No. 601.

Divided and this application December 29, 1952. Serial No. 328,477

6 Claims. (01'. z'ez s) This invention relates to the gasifi'cation of coal in underground formations. In one specific embodiment it relates to the method of making gas mixtures rich in hydrogen and carbon monoxide by the reaction of methane with steam, methane with carbon dioxide, or controlled partial oxidation of methane with air or oxygen.

Other specific aspects involve the novel apparatus employed in producing various valuable gases from coal by underground gasification and/or burning of the coal in situ.

The present application is a division of my copending application Serial No. 601, filed January 5, 1948, now abandoned, for Method and Apparatus for Gasifying Coal."

Numerous valuable chemical processes are being developed in the United States and elsewhere employing socalled synthesis gas or other gaseous mixtures rich in hydrogen and carbon monoxide, which gases are reacted in various chemical processes to producehydrocarbons, alcohols and other products of value. Also gases rich in hydrogen and/or carbon monoxide are valuable as fuels. At the same time many coal deposits in the United States and elsewhere cannot be mined in a profitable manner by ordinary mining methods because of the low grade of the coal, the thinness of the coal scam, the steep angle of dip of the seam, the tendencies to spontaneous combustion, dangerous gas content, high ash content, or other disadvantageous or hazardous I characteristics. While the coal deposits valuable for conventional'minin'g' are relatively restricted in area, there is practically, an unlimited amount, of low grade coal in thin seams which is not worth mining; A number of plans for underground gasification of such coal have been made in' the' prior art and it is understood that some of these plans have been tried out in Russia. None of these prior art plans for underground gasifi'ca-tion of coalfhas ever achieved any commercial success and Workers in this field have been unable to determine exactly what is wrong with the proposed processes. I, I

I have found that the reason for failure of the prior art methods to produce operable results is that they are incapable of operating at a temperature high enough to properly carry out the reactions necessary toproduce the desired product or products. For example, one of the chief reactions involved is the reaction of methane with steam to form hydrogen and carbon monoxide according to the following formulae:

In order for this'reacti'on to occur properly a temperature preferably above 1500 F. is desirablebecause with a temperature ofab'ou ti 1200 F. the" reaction tends to'follow the following equation:

In the absence 6r catalysts therate of he m thane steam reaction" is" saidtc' be slow, becoming appreciable only at temperatures above 2370 F. While same under-- I 2,766,666 P t dNa 6 19 ice 2 ground deposits may: have. catalytic value, generally: the underground gasification of coal may be regarded as more nearlynon-catalytic than catalytic. I II I I Obviously, other reactions are occurring along with the two reactions with steam mentioned above, such as the reaction with carbon dioxide: I I I I I (3) CHM-CD2+ 2CO+2H2 ('60 K calsL) And some controlled oxidation: I I (4) 2CI-I4+Oz 2CO+4Hi (-F -7.2 K calls.) I

Another reaction which takes place is a combination reaction according to the following equation:

I have found that the diificul-ty in the priorart S 1 9i capable of solution by merely increasing the amount. of air as the relative heat losses are roughlyv inversely proportional to the square root of the intensity of gasifica; tion. The presentinvention is a solution to the difiiculties of the prior art by supplying streams of air or oxygen and/or steam or other gases or fluids at high pressures in the vicinity of the point at which the combustion is taking place so that said combustionor gasification of the coal may be v controlled. in such manner as to produce a better product uiithl'essexpense and difficulty. flhe apparatus of the present invention provides for. moving the point of application of the high pressure fluids so that a progressive. process may be practiced enabling temperature control whichwillniaintain the temperature of reaction' at a level more nearly optimum to the desired reae: tions and thereby minimize the undesired reactions which occur.

O ne object of the present invention isto provide apparatu'sfor' theunderg'rou'nd gasification of coal. I i I v I.

Another object is topr'ovide such apparatus asisfparticularly useful in coal seamsf that are unprofitabletowork by ordinary mining methods, especially low grade coal, coal inthin seams, coal seams dipping sharply, gassy coal, coal, having a tendency to spontaneouscom bustion, coal having aihigh ash content ,.or.coal having other characteiistics making mining unprofitable How: ever, it should be undr'stood'that myrapparatus ispere, fectlyI capable ,of operation'in coalj'seamsf suitablelfon mining, and with proper development, it is an objectof my invention to provide means capable of competing with presentsyst'ems of mining coal; r I

A further object is' to provide apparatusand means for operating the same to'practice methods that will per: mit more complete recovery of coal in' situin the form of'valuable gases. I I Y Another object is toflprovide suitable apparatus for gasifiyng coal underground. I I

Numerous other objects and advantages will be apparent to those s killed in the art upon reading the accompanying specification, drawings and claims.

In the drawings: I

Figure 1 is a cross sectional elevational view taken through? PO fthd earth' containinga coal seam showing apparatus embodying Certain aspects of the-pres ent, invention and, illustrating onefpoint inthe operation ofa' method embodying specific aspects of the presentinv ii i n Figure 2 is a cross sectional view of one'formcf jet tube which is shown in Figurejl.

Figure 3 is a view similar to Figure 2 of a' second iYP, of jet tube which may be employed in the practice of thisinventi'on. I

Figure 4 is a qu r ri 'awed e ev ti nal V ew; of a our form of jet, tube which'ma'y be employed in thep'rfacticc. of the presentinventio Figure 5 is" an" elevational view of't'ap' ed l" the jettubes of Figures 1 to 4, inclusive, when it is desired to modify direction of the jet action.

Figure 6 is a cross sectional view of a portion of the earth showing how the methods and apparatus of the present invention may be adapted to use in the deflected well.

Figure 7 shows a preferred position for a drill hole or burned hole in a coal seam.

Figure 8 is a cross sectional elevational view of a por tion of the earth showing a modified form of apparatus being employed in burning a hole in the lower portion of the coal seam.

Figure 9 is a cross sectional view taken through one of the valve units employed in the apparatus shown in Figure 1. a 1

In Figure l a cross section of earth formations generally designated as 11 may contain non-productive earth formations 12 and 13 and a vein or seam of coal 14. Coal seam 14 may be one that is either profitable or unprofitable to mine by conventional mining methods, as the present invention applies to either type of coal seam; however, the present invention has a special value when the coal seam 14 is of a type unprofitable to mine by conventional mining methods.

In coal seam 14 a hole 16 has been drilled by any conventional method of drilling holes, or holes 16 may be burned into coal by methods to be discussed later. Hole 16 may be in the center of the coal seam as shown but often it is preferably located in the lower portion of the coal seam as will be explained with relation to Figure 7 later in this disclosure. Air or oxygen from tank 17, fuel gas from tank 18, and/or steam from boiler 19 in any combination or singly may be introduced into hole 16 through a pipe 21 as will be set forth later.

Pipe 21 comprises a jet nozzle portion 22, pipe sections 23 and valve connector sections 24. The valve connector sections 24 are more fully illustrated in Figure 9.

' The fluid or fluids being forced into hole 16 through pipe 21 emerge from radial jet holes 26 in the jet nozzle 22 and burn, erode and otherwise enter coal vein 14 along planes 27, causing a rapid burning or gasification of the coal to proceed at a relatively high temperature whereby optimum amounts of gas having a valuable composition are produced and the coal 14 is reduced to ashes and/ or coke 28. When the coal 14 is reduced to ashes 28 at a point adjacent jet nozzle 22, the jet nozzle is then moved through hole 16 to a new position where it will operate on fresh coal, and this movement may be either uniform or by steps as desired, as will be explained below.

' As the coal is gasified the gases pass out hole 16 and around the outside of pipe 21 and are collected by a casing head 29 which may be sealed to the coal seam 14 by any conventional means, such as cement. Casing head 29 has a stufiing box 31 and stutfing box follower 32 for packing around pipe 21 especially as pipe 21 is moved in or out of hole 16.

Casing head 29 is provided with a product fiow line 33 which may have the usual pressure gauge 34. Line 33 may lead through a suitable cut-off valve 36 into a gas holder 37 from which the gas may be withdrawn through a product line 38 controlled by valve 39 for use as fuel gas or as a reactant gas in a Fischer-Tropsch or other chemical process (not shown). Gas holder 37 is shown with a conventional floating roof 41 but obviously any type of gas holder may be employed.

In order to provide information as to the value of gas being produced, which information may also be valuable in directing the control of the process, it is desirable to sample the gas in conduit 33 by means of a sample line 42 controlled by valve 43 which leads to any suitable type of gas analyzing apparatus 44. Such analyzing apparatus is well known to the art'an'd, therefore, is not described further except to state that gas may be analyzed for the amount of water, carbon monoxide, carbon, di

oxide, hydrogen, oxygen, nitrogen, methane and other products which it may be expected to contain.

Gas (such as fuel gas) may be supplied from tank 18 through conduit 46 controlled by valves 47 and 48 and pressure regulator 49 to a manifold 51 from which it may be introduced into pipe 21 through either or both flexible hose 52 and 53 controlled by valves 54 and 56 all in the manner as will be more fully described with reference to Figure 9.

Steam from boiler 19 is similarly supplied to manifold 51 through conduit 57 controlled by valve 58 and pressure regulator 59. Boiler 19 may, of course, be supplied with all the usual equipment such as relief valve 61 and pressure gauge 62.

In a similar manner oxygen from the tank (not shown) or from an oxygen producing plant (not shown) may enter the system at 63 and be compressed by compressor 64 and stored in tank 17 which may be provided with a relief valve (not shown), pressure gauge 66 and other regular equipment. From tank 17 the air or oxygen may pass through a regulator 67 and conduit 6% controlled by valve 69 into manifold 51, and'the pressure in manifold 51 is indicated by pressure gauge 71.

Figure 2 shows the jet nozzle 22 of Figure l on a large scale and with parts in cross-section broken away to show details of construction. While in many instances nozzle 22 can be made out of steel or other metal, I prefer to make the same out of a hard ceramic material which is capable of withstanding higher temperatures than metal and this is of particular value when oxygen is being ernployed in the burning out process as sometimes when oxygen is being introduced through a steel pipe, the pipe may catch fire and burn or become melted in some way or other. In the form shown in Figure 2, nozzle 22 has closed or blank end 72 and a hollow interior 73 communicating with the interior of pipe 21 to receive fluids therefrom. Nozzle 22 is, of course, provided with jet holes 26 which direct fluids emerging therefrom as radial jets. The nozzle 22 may be provided with a thermocouple 74 having an electric cable 76 connected to a suitable indicating instrument as will be shown in Figure 8.

Figure 3 shows a modified type of jet nozzle '77 having radial jet 78 but also having axial jet 79 and other forwardly directed jets'81. 77 is preferably made of steel or other material of considerable strength because jet 77 is employed in modified forms of my process in which the hole is burned into coal by the progress of jet 77 instead of having the hole 16 first drilled and jet 22 merely inserted and withdrawn in a preformed hole.

Figure 4 shows a third modification of a nozzle 82 pro-- vided with radial jet holes 83 and forwardly directed jet holes 84. Surrounding nozzle 32 is a sleeve 86 containing inlet holes 87 so that the products of combustion may be removed through annular space 88 and their temperature taken by thermocouple 74 as they enter space 83. This type of nozzle shown in Figure 4 is adapted to practice either the withdrawal operation in a preformed hole 16 or may be used to burn a hole through the coal, and in both instances the products of combustion are removed through annular space 88.

Figure 5 is an elevational view of a tapered plug 89 which may be used to plug any undesired holes in the nozzle as shown in Figure 4. For example, holes 79 and 81 of Figure 3 may be plugged to provide a nozzle of the type having only radial holes, or the lower holes may be plugged in a nozzle so that the major portion or all of the fluid passing out through the nozzle may be directed upwardly which is preferable in many instances.

Figure 6 shows how the invention may be employed in a directional drill hole extending through non-productive formation 91 into coal vein 92 which lies between forma tions 91 and 93. A conventional drilling rig 94 may be employed to sink a well 96 which well is deflected by any conventional method such as whipstocking at 97 into more or less horizontal bore 98 in the coal seam 92. Either hsarnsratus qt Fisars 1 ortha f. F g 8 ay be 9 3.- nIQy c1; "If't a pa at s o i u e 1 ssm l yed 1H 19 enient to. more t e asin a 29 a the surftw.e of the ground. In either instance after the bore 98 is in the coal seam it may be extended therein by conventional drilling Proc sses. 01' by burning.

' In Figure 7 a coalsearn 99 is located between earth formations 101 and 102. and the bore hole or hole being burned 103; is located adjacent the bottom of the coal searn which is preferable in many instances as later burniiig or gasification of the coal occurs more easily in the upper direction in seam 99 because of the convection of hot products upwardly and cold products downwardly due to difierence in specific gravity. Bore 103 may rest on formation 102 which may be a hard formation as will be explained with relation to Figure '8.

In Figure 8 a hole is being burned to the right in coal seam 104 loeated between earth formations 105 and 106 by a nozzle 107 on the end of a flexible conduit 108 insorted in a shaft 109. Flexible conduit 108 is coiled on a druinllll mounted .on a truck 112 and fluids are supplied through conduit 108 by a pipe 113 leading to the inner end of the .conduit 108 on drum 111 by suitable stuffing box arrangement. Nozzle 107 is provided with a thermocouple74 (not shown) and the wires from the thermocouple lead to slip rings 114 and 116 on drum 111 from which suitable brushes pick up the potential developed and carry the same through wires 117 and 118 to a suitable indicating instrument 119. As shown in the drawings, steam from boiler 121, gas from gas container 122 and/ or oxygen from container 123 may be supplied in any, proportion to the conduit 108.

In Figure 9 the valve connection 24 of Figurel is shown in greater detail. Valve connection 24 is provided @XtErnally threaded ends 124 and contains a bore 12 havingan axial valve seat 127 and a radial bore 128. Radial bore 128 may be closed by a plug 129 or may be eonnected to one of conduits 52 or 53, of Figure 1 by ineans-ofa valve connection 54 or 56. In connection 24 avalve 131 is pivoted at pivot 132 to swing from the pp tion shown in; which it closes bore 128 to a vertical Nat o -in h t wi close bore 127 epe g pon thprelativepressure of fluids inb ores 1-27 and 128 as will he explained under the operation of the" invention.

Operation 1 In Figure 1 a bore hole 16 has been driven into the coal seam 14 either by drilling the bore hole with any conventionaldrilling equipment, such as a diamond core drill (not show-n) or hole 16'may have been burned into the formation by a method similar to that shown in Figure 8. Regardless of how hole 16 is produced the method in Figurea is as follows: Agas conducting conduit 21 is assembled out of pipes 23 andvalved joints 24 with a jet nozzle 22 on its end and is inserted into bore hole 16 through stuffing box 31, 32of sealing head 29. During this insertion air from pipe 68 and gas-from pipe 46 may be forced through conduit 2'1fland having once been ignited by a match (not shown) willb urn as it emerges from jets 26. -T he operation of valves 24 will be apparent from Figure9. Valve head 131 is pivoted at 132 and will seat close either passage 127 or passage 128 dependingon which passage contains gas at the greater pressure. Ob.- 9l ya' x zbssd ses the Pass having the least pressure, being-blown shut against said passage by the-flow ofgas from theother passage through opening 126, Returning-to Figure 1 with valve 56 rclosedand valve '54 open, gases from manifold 51 pass through flexihie condnit-fl and blow valve head 131 against seat 127 thn forcin jthe gases toproceed. through pipe 21 and to $5 119!! 91 263$ jets,- The gases cannot travel to the new-section. of pipe 23 which is? being added. .emvalve section 24 is attached and valve 56 i Qll d valve 54 9 9? ih p t e E?! .P through flexible conduit 53" id 'blovvs the valve'head 131 inthe right hand valve 24 tc'close seat 127 whereas inall of the other valves 24 the valve head 131 is being blown against seat 128. Valve 54 is then removed from valve section 24 and in order to obviate any difiiculty the plug 129 is screwed into 24 to close opening. 128 in a secure manner. Valve heads 131 act as check valves preventing backward flow through pipe 21 in case of any underground explosion.

Flexible conduit 52 and valve 54 are then free to be attached to the next valve 24 after the next pipe section 23 has been attached. In a similar and obvious manner the reverse of this process may be employed in removing pipe 21 section by'section without at any moment inter: rupting the flow of gases therethrough.

Having inserted pipe 21 With a. flame burning at the end through hole 26 into the coal seam preferably to the entire extent of hole 16, it is then preferred to admit air or oxygen from line 68 under increased pressure causing localized burning of the coal inseam 16 adjacent jets 26. When the coal has begun to burn valve 48 may be closed, turning off gas 18,.

It is not believed necessary to go into the various reactions which take place as coal burns in accordance with the amount of oxygen, nitrogen, water vapor and combustion gases which may be present. It is generally con sidered that the coal may break down to methane (CH4) but this is not necessarily true in order to practice applicants invention, which invention does not consist in any theory but which consists incertain process steps or combination of apparatus. The only purpose of mentioning a theory is merely to classify the operation of the invention.

In accordance with the theory that the coal will break down into methane, five equations have been given above. Equations 1, 3, 4 and 5 are desirable and obviously Equation 2 is undesirable. In order to avoid Equation 2 the temperature at the point of reaction should be above 1500 F., or at least closer to 1500 F. thanto 1200" F. because at 1200 F. the reaction tends to obey Equation 2.whereas at 1500 F., and above, Equation 5 is favored, but the temperature at the point of burning should also be below 2370 F. where EquationZ is again favored.

Jets 26 increase the intensity of burning of coal seam 14 so that the desired temperature may be maintained and this temperature may be estimated by readings taken with a thermocouple 74. When the desired temperature is achieved, water vapor preferably in the form of steam may be admitted to the system throughvalve 58.

In a certain length of time the coal in seam 14 adjacent jets 26 is burned to ashes 28 which may or may not contain a certain amount of coke. Either continuously during the burning operation, or in spaced steps, the pipe 21 is withdrawn from hole 16 placing jets 26 opposite fresh unburned coal where the jets start burning crevices 27 back into the coal, igniting the same and turning it into ashes 28.

All of the time that this burning and various reactions are taking place the reaction gases are travelling through hole 16 around pipe 21 into head 29 and through pipe 23 to a gas holder 37 of the usual type. The pressure of the gas is preferably indicated on gauge 34 and samples of the gas being produced are preferably'analyzed in the gas analyzer 44.. At the same time the composition of gases entering through valve 48, 58 and 691's preferably known and the pressure thereofis preferably measured bygauge71.

The process, therefore, can be- -controlled'by various relationships, such as the difference in pressure between gauges 34 and 71, which will indicate the progress of the burning and also control can be obtained 'by readings from thermocouple 74 which indicates the temperature and also the progress of the burning. Also gas analyzer 4-4 may be employed .to indicate nature and degree-of the burning. When all ar'e'nsed, 'in combination these various indicating means give afvery thorough picture of what is going on so that the engineer may make desirable changes in the factors involved.

The gas in gas holder 37 is commercially valuable, consisting mostly of carbon monoxide and hydrogen with or without dilution by nitrogen depending on whether air or oxygen was introduced to the system through pipe 63. Generally it is economically preferable to employ air especially when gas 37 is to be used as fuel gas, and especially when coal seam 14 is shattered so that extraneous air can enter the system. When the gas in gas holder 37 is to be employed in chemical reaction (for example, of the Fischer-Thopsch type) it is often desirable to employ oxygen in which case there is less nitro gen in the gas. The gas is taken through pipe 38 and valve 39 to whatever type of process the gas is to be employed for.

"When pipe 21 is completely removed from coal seam :14, another hole 16 is bored in some other portion of the coal seam and the process is repeated. The operation of the device shown above ground in Figure l is believed obvious. 18 is any source of gas suitable for fuel. This gas may come from an oil well, pipe line, commercial gas plant, or be gas from gas holder 37 produced from another portion of coal seam 14. The pressure of this gas may be regulated at 49. 19 similarly is any source of steam and may be a boiler as shown or may be steam generated by some process utilizing gas from gas holder37 (process not shown). Similarly tank 17 may contain any combination of air and/ or oxygen which may come from an oxygen plant (not shown) attached to pipe 63. If desired additional pumping means may be employed in pipes 33, 46, 57 and 68, and a pumping means (not shown) in pipe 33 may be employed to operate hole 16 at a vacuum if desired.

The operation of Figure 6 is similar to that of Figure '1 except that hole 98 replaces hole 16 and hole 98 is drilled by a means of drilling a well 96 in a vertical direction through formation 91 and deflecting the same by whipstocking at 97, or other well known deflective hole drilling methods.

The method shown in Figure 7 is adaptable to the method shown in Figure l and Figure 6 as Figure 7 merely emphasizes the desirability in many instances of running hole 103 at or near the bottom of coal seam 99 because, as well known, the burning of coal or other substances generally proceeds in an upward direction due to the fact that hot gases are lighter than cold gases and, therefore, are forced upward by the heavier cold gases. In order to direct these gases upwardly from the jets into coal 99 it is often desirable to plug some of the jet holes 26 and this may be done by employing tapered plugs such as 89 of Figure which plugs may be placed in any of the holes shown in Figures 1, 2, 3, 4 and 8.

When employing the nozzle shown in Figure 4 it is not necessary to have a housing such as 29 as the combustion gases enter holes 87 and are drawn olf through space 88 preferably by a vacuum purnp of some type.

' In the method shown in Figure 8 a portable apparatus 112 supplies steam, gas or air in the desired proportions to the end of hose 108 reeled on reel 111 and this flexible hose 108 may be forced into the coal so that a hole is burned in the coal by flames coming out of nozzle 107. When this hole has been burned back into the coal a sufficient distance a split housing (not shown) similar to housing 29 may be placed around hose 1% and then with increased air pressure hose 1% may be withdrawn slowly through the coal 104, the burning of which with or "without the presence of steam from boiler 121 will produce valuable gases in the manner described relative to Figure l.

When burning holes in the coal, it is often preferred use jets such as shown in Figures 3 and 4 in which there are forwardly directed holes 79, 31 and 34. These forwardly directed holes can be plugged with plugs 89 if desired before burning the coal and withdrawing the pipe. However, in the process of burning the coal and withdrawing the pipe it isoften preferable to employ '3 nozzle 22 made of ceramic material as illustrated in Figure 2 because such material is capable of withstanding higher temperatures which is also especially valuable when using oxygen in pipe 68 as it is Well known that a steel pipe will burn if oxygen is being injected through it and it reaches sufficient temperature.

While I have described above certain specific forms and apparatus and certain specific sequences of process steps, it is understood that this has been done in order to give illustrative embodiments to the invention and that the invention is not limited thereby but instead is of a scope defined and limited only by the following claims.

Having described my invention, I claim:

l. A system for .the underground gasification of coalin a coal vein which comprises a tube having a jetting nozzle having radial jets therein adapted to be disposed in said coal vein, a casing head sealed to said coal vein and to said tube, said tube comprising a plurality of connected and communicating sections, each section having an axial passage in communication with the next section and a radial passage communicating with said axial passage, check valve means controlling flow through said passages so that continued flow through said axial passage away from said nozzle and from said axial passage out through said radial passage is checked, at source of steam, a source of fuel gas, and a source .of free oxygen containing gas, a manifold connecting said sources with at least one of said radial passages comprising two flexible conduits whereby fluids from said sources may be continuously supplied to said nozzle without interruption during the insertion and withdrawal of said tube through said casing head.

2. A system for the underground .gasification of coal in a coal vein which comprises a tube having a jetting nozzle adapted to be disposed in said coal vein, a casing head sealed to said coal vein and to said tube, said tube comprising a plurality of connected and communiouting sections, each section having an axial passage in communication with the next section and a radial passage communicating with said axial passage, check valve means controlling flow through said passages so that continued flow through said axial passage away from said nozzle and from said axial passage out through said radial passage is checked, a source of fuel gas, and a source of free oxygen containing gas, a manifold connecting said sources with at least one of said radial passages comprising two flexible conduits whereby fluids from said sources may be continuously supplied to said nozzle without interruption during the insertion and withdrawal of said tube through said casing head. j

3. A system for the underground gasification of coal in a coal vein which comprises a tube having a jetting nozzle adapted to be disposed in said coal vein, a casing head sealed to said coal vein and to said tube, said tube comprising a plurality of connected and communicating sections, each section having an axial passage in corn munication with the next section and a radial passage communicating with said axial passage, check valve means controlling flow through said passages so that continued flow through said axial passage away from said nozzle and from said axial passage out through said radial passage is checked, a source of steam, and a source of free oxygen containing gas, a manifold connecting said sources with at least one of said radial passages comprising two flexible conduits whereby fluids from said sources may be continuously supplied to said nozzle without interruption dur-' ing the insertion and withdrawal of said tube through said casing head. l

4. A system for the underground gasification o f coal in a coal vein whichcomprises a tube having a'jefting nozzle adapted to be disposed in said coal vein, a casing head sealed to said coal vein and to said tube, said tube comprising a plurality of connected and communicating sections, each section having an axial passage in communication with the next section and a radial passage communicating with said axial passage, check valve means controlling flow through said passages so that continued flow through said axial passage away from said nozzle and from said axial passage out through said radial passage is checked, a source of free oxygen containing gas, a manifold connecting said source with at least one of said radial passages comprising two flexible conduits whereby fluid from said source may be continuously supplied to said nozzle without interruption during the insertion and withdrawal of said tube through said casing head.

5. A system for the underground gasification of coal in a coal vein which comprises a tube having a jetting nozzle having radial jets and forwardly directed jets therein adapted to be disposed in said coal vein, a casing head sealed to said coal vein and to said tube, said tube comprising a plurality of connected and communicating sections, each section having an axial passage in communication with the next section and a radial passage communicating with said axial passage, check valve means controlling flow through said passages so that con tinued flow through said axial passage away from said nozzle and from said axial passage out through said radial passage is checked, a source of steam, a source of fuel gas, and a source of free oxygen containing gas, a manifold connecting said sources with at least one of said radial passages comprising two flexible conduits whereby fluids from said sources may be continuously supplied to said nozzle without interruption during the insertion and withdrawal of said tube through said casing head.

6. A system for the underground gasification of coal in a coal vein which comprises a tube having a jetting nozzle having radial jets therein adapted to be disposed in said coal vein, a casing head sealed to said coal vein and to said tube, said tube comprising a plurality of connected and communicating sections, each section having an axial passage in communication with the next section and a radial passage communicating with said axial passage, check valve means controlling flow through said passages so that continued flow through said axial passage away from said nozzle and from said axial passage out through said radial passage is checked, an annular sleeve having inlet holes and surrounding said tube, said sleeve axially extending from said nozzle to said casing whereby the products of combustion may be removed through the annular space defined by said annular sleeve and said tube, a source of steam, a source of fuel gas, and a source of free oxygen containing gas, a manifold connecting said sources to at least one of said radial passages comprising two flexible conduits whereby fluids from said sources may be continuously supplied to said nozzle without interruption during the insertion and withdrawal of said tube through said casing head.

7. A system for the underground gasification of coal in a coal vein which comprises a tube having a jetting nozzle having radial jets therein adapted to be disposed in said coal vein, a casing head sealed to said coal vein and to said tube, said tube comprising a plurality of connected and communicating sections, each section having an axial passage in communication with the next section and a radial passage communicating with said axial passage, check valve means controlling flow through said passage so that continued flow through said axial passage away from said nozzle and from said axial passage out through said radial passage is checked, an annular sleeve having inlet holes and surrounding said tube, said sleeve axially extending from said nozzle to said casing whereby the products of combustion may be removed through the annular space defined by said annular sleeve and said tube, a thermocouple in said annular space generally adjacent said nozzle, a source of steam, a source of fuel gas, and a source of free oxygen containing gas, a manifold connecting said sources to at least one of said radial passages comprising two flexiole conduits whereby fluids from said sources may be continuously supplied to said nozzle without interruption during the insertion and withdrawal of said tube through said casing head.

8. A system for the underground gasification of coal in a coal vein which-comprises a tube having a jetting nozzie having radial jets and forwardly directed jets therein adapted to be disposed in said coal vein, a casing head sealed to said coal vein and to said tube, said tube comprising a plurality of connected and communicating sections, each section having an axial passage in communication with the next section and a radial passage communicating with said axial passage, check valve means controlling flow through said passages so that continued flow through said axial passage away from said nozzle and from said axial passage out through said radial passage is checked, an annular sleeve having inlet holes and surrounding said tube, said sleeve axially extending from just back of said nozzle to said casing whereby the products of combustion may be removed through the annular space defined by said annular sleeve and said tube, a thermocouple in said annular space generally adjacent said nozzle, 21 source of steam, a source of fuel gas, and a source of free oxygen containing gas, a manifold connecting said sources to at least one of said radial passages comprising two flexible conduits whereby fluids from said sources may be continuously supplied to said nozzle without interruption during the insertion and withdrawal of said tube through said casing head.

References Cited in the file of this patent UNITED STATES PATENTS 947,608 Betts Jan. 25, 1910 1,244,030 Cave Oct. 23, 1917 1,325,116 Sebille Dec. 16, 1919 1,559,934 Bosch Nov. 3, 1925 1,666,488 Crawshaw Apr. 17, 1928 1,702,546 Owens et al Feb. 19, 1929 1,839,515 Weatherbee Ian. 5, 1932 1,913,395 Karrick June 13, 1933 2,193,893 Van Vleck Mar. 19, 1940 2,284,603 Belchetz et al. May 26, 1942 2,466,945 Greene Apr. 12, 1949 2,481,051 Uren Sept. 6, 1949 2,497,868 Dalin Feb. 21, 1950 2,695,163 Pearce et al. Nov. 23, 1954 FOREIGN PATENTS 200,423 Germany July 17, 1908 OTHER REFERENCES Experiment in Underground Gasification of Coal, Gorgas, Ala.; Report of Investigations, Bureau of Mines R. I. 4164, Aug. 1947, especially pages 6, 28 and 42.

Fuels and their Combustion Haslam and Russell, 1st ed. 1926; pgs. 162-165.

The Gas World, No. 25, 1944 (pg. 547). 

1. A SYSTEM FOR THE UNDERGROUND GASIFICATION OF COAL IN A COAL VEIN WHICH COMPRISES A TUBE HAVING A JETTING NOZZLE HAVING RADIAL JETS THEREIN ADAPTED TO BE DISPOSED IN SAID COAL VEIN, A CASING HEAD SEALED TO SAID COAL VEIN AND TO SAID TUBE, SAID TUBE COMPRISING A PLURALITY OF CON-L NECTED AND COMMUNICATING SECTIONS, EACH SECTION HAVING AND AXIAL PASSAGE IN COMMUNICATION WITH THE NEXT SECTION AND A RADIAL PASSAGE COMMUNICATING WITH SAID AXIAL PASSAGE, CHECK VALVE MEANS CONTROLLING FLOW THROUGH SAID PASSAGES SO THAT CONTINUED FLOW THROUGH SAID AXIAL PASSAGE AWAY FROM SAID NOZZLE AND FROM SAID AXIAL PASSAGE OUT 